Doors, tailgates, hoods, and the like that have a substantial weight and which open and close by use of a hinge or similar arrangement are typically counterbalanced by use of a spring. In several common arrangements, the spring is used to counterbalance the forces associated with the opening and closing of doors, tailgates, hoods, and the like, and to further reduce the force needed to open and close the doors, tailgates, hoods, and the like.
Tailgates and hoods are commonly mounted to vehicles by use of a hinge and pivot between an opened and closed position to grant access to a cargo area or engine compartment. In the past, chains, cables or articulated brackets have been used to limit the opening of the tailgate. However, devices do not provide any counterbalancing force to facilitate in the opening and closing of the tailgate. Gas springs or struts have been used in the past to assist in opening and/or closing tailgates and hoods. However, such gas springs or struts are problematic when used with tailgates that are subjected to loads when the tailgate is in an opened position. The gas springs or struts may not withstand such loadings, especially when the vehicle is being operated. In addition, gas springs and struts are affected by ambient temperatures. As such, when the temperature changes, the forces applied by the gas springs or struts also changes. The change in forces can result in difficulty in opening and/or closing the hood or tailgate, or can result in damage to the tailgate or hood when opening or closing the tailgate or hood.
Elastic elements such as springs are also commonly used to provide counterbalancing forces during the opening and closing of the doors, hoods and tailgates. When such springs are used with doors and tailgates, the spring can be damaged when the door is opened too wide, and when large loads are exerted on the tailgate in an opened position. Extension springs are designed to provide a certain load and/or deflection, thus assigning a certain rate to the spring. As a result, the amount of travel of the spring is controlled by the rating of the spring. Extension springs are typically comprised of round wire that is tightly coiled or pitched (open coils). These springs have a maximum extension point. Exceeding such a maximum extension point results in damage to the springs. As a result, the springs cannot provide a solid stop, nor can the springs handle or be exposed to large loads in their extended state. Another elastic element that is sometimes used is a rubber band or bungee cord. However, as with extension springs, rubber bands or bungee cords cannot provide a solid stop, nor can the rubber bands or bungee cords handle or be exposed to large loads in their extended state.
Several arrangements have been developed to minimize the damage to springs resulting in over extension of the spring. One such arrangement is disclosed in U.S. Pat. No. 5,810,339. In this arrangement, two draw yokes are used to minimize over extension of the spring. However, the yoke assembly limits the travel of the assembly to no more than double the length of the assembly in a non-extended state. Other types of solid stop arrangements that include stiff, high-strength materials (e.g. metals) limit the travel of the counterbalance assembly by imposing a stop that is no more that double the length of the assembly in a non-extended state. If travel of the assembly is to be more than twice the length of the non-extended assembly, these existing solid stops cannot be used.
In view of the state of the art of assemblies used in association with doors, hoods and tailgates of a vehicle, there is a need for an assembly that provides counterbalancing forces to facilitate in the opening and/or closing of doors, hoods and tailgates, and which provides a solid stop to prevent over extension of the elastic material in the assembly without necessarily limiting the extension of the assembly to only twice the length of the non-extended assembly.